linux-kernel - Re: [PATCH v2 0/2] "no-hpd" support in CDNS DP bridge driver

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Message-ID: <b974c741-9d3e-1229-bcd5-a980035d1fb4@ideasonboard.com>
Date:   Mon, 17 Apr 2023 11:47:39 +0300
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Jayesh Choudhary <j-choudhary@...com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, krzysztof.kozlowski@...aro.org
Cc:     andrzej.hajda@...el.com, neil.armstrong@...aro.org,
        rfoss@...nel.org, Laurent.pinchart@...asonboard.com,
        jonas@...boo.se, jernej.skrabec@...il.com, airlied@...il.com,
        daniel@...ll.ch, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, sam@...nborg.org,
        jani.nikula@...el.com, tzimmermann@...e.de, javierm@...hat.com,
        ville.syrjala@...ux.intel.com, r-ravikumar@...com,
        lyude@...hat.com, alexander.deucher@....com, sjakhade@...ence.com,
        yamonkar@...ence.com, a-bhatia1@...com
Subject: Re: [PATCH v2 0/2] "no-hpd" support in CDNS DP bridge driver

On 05/04/2023 17:24, Jayesh Choudhary wrote:
> In J721s2 EVM, DP0 HPD is not connected to correct HPD pin on SOC
> which results in HPD detect as always connnected, so when display
> is not connected driver continuously retries to read EDID and DPCD
> registers.

Where is the DP0 HPD connected to? Nowhere? If it's connected to a pin, 
can that pin be used as a GPIO? In other words, do we have a HPD, just 
not with mhdp, or is there just no HPD at all?

  Tomi